Airborne pollutants from human and natural sources can deposit back onto land and water bodies, sometimes at great distances from the source, and can be an important contributor to declining water quality.Pollutants in waterbodies that may originate in part from atmospheric sources include nitrogen compounds, sulfur compounds, mercury, pesticides, and other toxics.

Both human and natural processes can lead to air pollution. Human, or anthropogenic, sources include the combustion of fossil fuels for power generation and transportation, the release of chemical byproducts from industrial and agricultural processes, and the incineration of waste. Natural processes that can release substantial amounts of pollutants into the air include volcanoes and forest fires.

Airborne pollution can fall to the ground in precipitation, in dust, or simply due to gravity. This type of pollution is called “atmospheric deposition” or “air deposition.” Pollution deposited from the air can reach water bodies in two ways. It can either be deposited directly onto the surface of the water (direct deposition) or be deposited onto land and be carried to water bodies through run off (indirect deposition). Once these pollutants are in the water, they can have undesirable health and environmental impacts, such as contaminated fish, harmful algal blooms, and unsafe drinking water.

Atmospheric Deposition Handbook

Downloadable handbook answers basic questions about air deposition and sources, how its significance can be assessed through existing information, monitoring and modeling, and how the information can be used in a management strategy.